Equal chance, no but you should get your ass kicked is an issue with me. Although I am not on the continent so I don't know the specifics. (Is Eponlyn about the same size as Carelia and Perdan=CE?)
Eponlyn has, I think, 5 regions, including one small city. Perdan has 25 or so, including three rich cities, and about 4-5 times as many nobles.
So not quite an exact parallel, but close enough, I guess.
If so, then I say how the odds should be in CE's favor by a lot, but currently its just about impossible as I can can't think of a single viable strategy against CE if being Carelia. Carelia vs CE, I can see Carelia never really winning the actual war, but there should be someway to end up in about a draw if Carelia had extremely good strategists and military leadership and all that. Right now, I can't think of a way with even say Caergoth helping that Carelia could end up in a draw. Should it be highly unlikely? Yes. Should be possible with a lot work, skill, and a little luck?
Not unless CE was ridiculously incompetent, sabotaging themselves, and Carelia were full of hyperactive, late-logging geniuses.
This shouldn't be ground-leveling but it should be balanced in the sense thats its not just a tactic for big realms thats useful for big realms.
....which is kinda what I said.